Marginal bone loss around implants retaining hinging mandibular overdentures, at 4-, 8- and 12-years follow-up

Aim: The aim of the present study was to study the effect of occlusal facto rs, oral hygiene, gender and age on the long-term maintenance of alveolar b one height around screw-shaped machined surface commercially pure (c.p.) ti tanium implants retaining hinging mandibular overdentures. Method: In this retrospective study a long-term (4-, 8-, up to 12-years) fo llow-up of such implant-retained overdentures was performed. From the popul ation of patients so treated at the University Hospital of the Catholic Uni versity Leuven, Department of Periodontology and Department of Prosthetic D entistry, 158 patients were selected on the basis of being treated before M arch 1994, and the availability of intra-oral radiographs (paralleling tech nique) present at abutment connection (baseline) and at years 4, 8, and 12. For each patient, all relevant clinical data were recorded, and measuremen ts of marginal bone height around the implants were performed on intra-oral radiographs by means of a digital sliding calliper. Results: Results indicated that only the factor "time" had a significant in fluence on marginal bone loss. The age and gender of the patients, dental/p rosthetic status in the antagonistic jaw oral hygiene variables, and locati on of the implants had no significant effect. Conclusion: The very high cumulative success rate (97.2%) and limited margi nal bone loss (on average 1.7 mm) after 12-years, encourage this kind of tr eatment using this type of implants.